1. Field of the Invention
A measuring apparatus for a power roller unit for a toroidal type continuous variable speed transmission according to this invention facilitates the work of assembling a toroidal type continuous variable speed transmission utilized, for example, as the speed change unit of a transmission for an automobile or a transmission for various industrial machines and also improves the assembling accuracy to thereby achieve an improvement in performance.
2. Related Background Art
It has been studied to use a toroidal type continuous variable speed transmission as shown in FIGS. 3 and 4 of the accompanying drawings as a transmission for an automobile. In this toroidal type continuous variable speed transmission, as disclosed, for example, in Japanese Utility Model Application Laid-Open No. 62-71465, an input side disc 2 is supported concentrically with an input shaft 1, and an output side disc 4 is fixed to the end portion of an output shaft 3 disposed concentrically with the input shaft 1. Trunnions 6a, 6b pivotally movable about pivots 5a, 5b lying at locations twisted relative to the input shaft 1 and the output shaft 3 are provided inside a casing containing the toroidal type continuous variable speed transmission therein.
That is, these trunnions 6a, 6b have the pivots 5a, 5b provided concentrically with each other on the outer sides of the opposite end portions thereof. Also, the base end portions of displaceable shafts 7a, 7b are supported on the intermediate portions of the trunnions 6a, 6b and the trunnions 6a, 6b are pivotally moved about the pivots 5a, 5b, whereby the angles of inclination of the displaceable shafts 7a, 7b are made adjustable. Power rollers 8a, 8b are rotatably supported around the displaceable shafts 7a, 7b supported on the trunnions 6a, 6b. These power rollers 8a, 8b are sandwiched between the mutually opposed inner sides 2a, 4a of the input side and output side discs 2 and 4. Each of these inner sides 2a, 4a has its cross-section forming a concave surface obtained by being rotated along an arc centering around the pivots 5a, 5b. The power rollers 8a, 8b formed into spherical convex surfaces and the inner sides 2a, 4a are in contact with each other. Hereinafter, the surfaces of the power rollers 8a and 8b which are in contact with the inner sides 2a and 4a, respectively, are referred to as the xe2x80x9cperipheral surfacesxe2x80x9d of the power rollers 8a and 8b. 
A pressing apparatus 9 of the loading cam type is provided between the input shaft 1 and the input side disc 2, and the input side disc 2 is capable of being elastically pressed toward the output side disc 4 by this pressing apparatus 9. This pressing apparatus 9 is comprised of a cam plate 10 rotatable with the input shaft 1, and a plurality of (e.g. four) rollers 12a, 12b, 12c and 12d (not shown) held for rolling by a holder 11. A driving side cam surface 13 which is a concavo-convex surface extending in the circumferential direction is formed on that surface (the left side as viewed in FIGS. 3 and 4) of the cam plate 10 which abuts against the holder 11, and a driven side cam surface 14 of a similar shape is also formed on the outer side (the right side as viewed in FIGS. 3 and 4) of the input side disc 2. The plurality of rollers 12a to 12d are supported for rotation about radial axes with respect to the center of the input shaft 1.
When during the use of the toroidal type continuous variable speed transmission constructed as described above, the cam plate 10 rotates with the rotation of the input shaft 1, the driving side cam surface 13 presses the plurality of rollers 12a, 12b, 12c and 12d toward the driven side cam surface 14 formed on the outer side of the input side disc 2. As the result, the input side disc 2 is pressed against the plurality of power rollers 8a, 8b and at the same time, the input side disc 2 is rotated on the basis of the pressing between the driving side and driven side cam surfaces 13, 14 and the plurality of rollers 12a, 12b, 12c and 12d. The rotation of this input side disc 2 is transmitted to the output side disc 4 through the plurality of power rollers 8a, 8b, and the output shaft 3 fixed to this output side disc 4 is rotated.
When the rotational speed ratio (change gear ratio) between the input shaft 1 and the output shaft 3 is to be changed and first, deceleration is to be effected between the input shaft 1 and the output shaft 3, the trunnions 6a, 6b are pivotally moved in a predetermined direction about the pivots 5a, 5b. The displaceable shafts 7a, 7b are then inclined so that as shown in FIG. 3, the peripheral surfaces of the power rollers 8a, 8b may abut against the rather central portion of the inner side 2a of the input side disc 2 and the rather outer peripheral portion of the inner side 4a of the output side disc 4, respectively. When conversely, acceleration is to be effected, the trunnions 6a, 6b are pivotally moved in the opposite direction about the pivots 5a, 5b. The displaceable shafts 7a, 7b are then inclined so that as shown in FIG. 4, the peripheral surfaces of the power rollers 8a, 8b may abut against the rather outer peripheral portion of the inner side 2a of the input side disc 2 and the rather central portion of the inner side 4a of the output side disc 4, respectively. If the angle of inclination of the displaceable shafts 7a, 7b is made intermediate of the angles shown in FIGS. 3 and 4, an intermediate change gear ratio is obtained between the input shaft 1 and the output shaft 3.
Also, FIGS. 5 and 6 of the accompanying drawings show an example of a more embodied toroidal type continuous variable speed transmission described in the microfilm of Japanese Utility Model Application No. 63-69293 (Japanese Utility Model Application Laid-Open No. 1-73552). An input side disc 2 and an output side disc 4 are rotatably supported around a tubular input shaft 15 through needle bearings 16. Also, a cam plate 10 is spline-engaged with the outer peripheral surface of one end portion (the left end portion as viewed in FIG. 5) of the input shaft 15, and the movement thereof away from the input side disc 2 is blocked by a flange portion 17. This cam plate 10 and rollers 12a, 12b together constitute a pressing apparatus 9 of the loading cam type for rotating the input side disc 2 while pressing it toward the output side disc 4 with the rotation of the input shaft 15. An output gear 18 is coupled to the output side disc 4 by keys 19, 19, and the output side disc 4 and the output gear 18 are rotated in synchronism with each other.
In FIG. 6, the opposite end portions of a pair of trunnions 6a, 6b are supported on a pair of support plates 20a, 20b for pivotal movement and displacement in an axial direction (the front-to-back direction of FIG. 5 or the left to right direction as viewed in FIG. 6). That is, radial needle bearings 22 which are first radial bearings are provided between the outer peripheral surfaces of pivots 5 secured to the opposite end portions of the trunnions 6a, 6b and the inner peripheral surface of a circular hole 21 formed in each support plate 20. The outer peripheral surfaces of outer rings 23 constituting these radial needle bearings 22 are fitted as spherical convex surfaces in the circular holes 21 for pivotal movement and axial displacement.
In this manner, the displaceable shafts 7a, 7b are supported in circular holes 24a, 24b formed in the intermediate portions of the trunnions 6a, 6b supported for pivotal movement and axial displacement between the pair of support plates 20a, 20b. These displaceable shafts 7a, 7b have support shaft portions 25a, 25b and pivotally supporting shaft portions 26a, 26b parallel to and eccentric from each other. The support shaft portions 25a, 25b are rotatably supported inside the circular holes 24a, 24b through radial needle bearings 27a, 27b which are second radial bearings. Also, power rollers 8a, 8b are rotatably supported around the pivotally supporting shaft portions 26a, 26b through radial needle bearings 28a, 28b which are third radial bearings.
The pair of displaceable shafts 7a, 7b are provided at locations opposite by 180xc2x0 relative to the input shaft 15. Also, the direction in which the pivotally supporting shaft portions 26a, 26b of these displaceable shafts 7a, 7b are eccentric relative to the support shaft portions 25a, 25b is the same direction (the right to left direction as viewed in FIG. 6) with respect to the direction of rotation of the input side and output side discs 2 and 4. Also, the direction of eccentricity is a direction substantially orthogonal to the direction of disposition of the input shaft 15. Accordingly, the power rollers 8a, 8b are supported for some displacement in the direction of disposition of the input shaft 15. As a result, even when the power rollers 8a, 8b tend to be displaced in the axial direction of the input shaft 15 (the left to right direction as viewed in FIG. 5 or the front to back direction of FIG. 6) due to the elastic deformation of the constituent members based on a great load applied to the constituent members in the transmitted state of the rotational force, this displacement can be absorbed without any unreasonable force being applied to each portion.
Also, between the outer sides of the power rollers 8a, 8b and the inner sides of the intermediate portions of the trunnions 6a, 6b, thrust ball bearings 29a, 29b which are first thrust bearings and thrust needle bearings 30a, 30b which are second thrust bearings are provided in series with one another with respect to the acting direction of a thrust load (a vertical direction as viewed in FIGS. 5 and 6), in the order from the outer sides of the power rollers 8a, 8b. The thrust ball bearings 29a, 29b support a load in the thrust direction applied to the power rollers 8a, 8b and yet permit the rotation of these power rollers 8a, 8b. Such thrust ball bearings 29a, 29b are comprised of a plurality of balls 31, circular ring-shaped retainers 32 retaining these balls 31 for rolling movement, and circular ring-shaped outer rings 33. The inner ring raceway tracks of these thrust ball bearings 29a, 29b are formed on the outer sides of the power rollers 8, and the outer ring raceway tracks of these thrust ball bearings 29a, 29b are formed on the inner sides of the outer rings 33.
Also, the thrust needle bearings 30a, 30b are comprised of races 34, retainers 35 and needles 36. The races 34 and the holders 35 are combined together for some displacement with respect to the rotational direction. Such thrust needle bearings 30a, 30b sandwich the races 34, between the inner sides of the trunnions 6a, 6b and the outer sides of the outer rings 33a, 33b with the races 34, abutting against the inner sides of the trunnions 6a, 6b. Such thrust needle bearings 30a, 30b support a thrust load applied from the power rollers 8a, 8b to the outer rings 33a, 33b and yet permit the pivotally supporting shaft portions 26a, 26b and the outer rings 33a, 33b to pivotally move about the support shaft portions 25a, 25b. 
Further, driving rods 37a, 37b are coupled to one end portion (the left end portion as viewed in FIG. 6) of the trunnions 6a, 6b, and driving pistons 38a, 38b are secured to the outer peripheral surfaces of the intermediate portions of these driving rods 37a, 37b. These driving pistons 38a, 38b are oil-tightly fitted in driving cylinders 39a and 39b, respectively.
In the case of the toroidal type continuous variable speed transmission constructed as described above, the rotation of the input shaft 15 is transmitted to the input side disc 2 through the pressing apparatus 9. The rotation of this input side disc 2 in turn is transmitted to the output side disc 4 through the pair of power rollers 8a, 8b and further, the rotation of this output side disc 4 is taken out from an output gear 18. When the rotational speed ratio between the input shaft 15 and the output gear 18 is to be changed, the pair of driving pistons 38a, 38b are displaced in opposite directions. With the displacement of these driving pistons 38a, 38b, the pair of trunnions 6a, 6b are displaced in opposite directions, and for example, the lower power roller 8b in FIG. 6 is displaced to the right as viewed in FIG. 6 and the upper power roller 8a in FIG. 6 is displaced to the left as viewed in FIG. 6. As the result, the direction of a tangential force acting on the contact portions between the peripheral surfaces of these power rollers 8a, 8b and the inner sides 2a and 4a of the input side disc 2 and the output side disc 4, respectively, is changed. With the change in the direction of this force, the trunnions 6a, 6b pivotally move in opposite directions about the pivots 5a, 5b pivotally supported on the support plates 20a, 20b. As the result, as shown in FIGS. 3 and 4, the contact positions between the peripheral surfaces of the power rollers 8a, 8b and the aforementioned inner sides 2a, 4a change, and the rotational speed ratio between the input shaft 15 and the output gear 18 changes.
The adjustment of the rotational speed ratio between the input shaft 15 and the output gear 18 to a desired value is effected by regulating the amounts of movement of the driving pistons 38a, 38b. The regulation of the amounts of movement of these driving pistons 38a, 38b is effected by the engagement between precess cams, not shown, fixed to the end portions or the intermediate portions of the driving rods 37a, 37b and the spools or the sleeves of spool values, not shown. Also, when as described above, the transmission of the rotational force is to be effected between the input shaft 15 and the output gear 18, the power rollers 8a, 8b are displaced axially of the input shaft 15 on the basis of the elastic deformation of each constituent member and the displaceable shafts 7a, 7b pivotally supporting these power rollers 8a, 8b slightly rotate about the support shaft portions 25a, 25b. As the result of this rotation, the outer sides of the outer rings 33a, 33b of the thrust ball bearings 29a, 29b and the inner sides of the trunnions 6a, 6b are displaced relative to each other. Since the thrust needle bearings 30a, 30b are present between these outer sides and inner sides, the force required for this relative displacement is small. Accordingly, the force for changing the angles of inclination of the displaceable shafts 7a, 7b as described above may be small.
When assembling the toroidal type continuous variable speed transmission constructed and acting as described above, the constituent parts have heretofore been assembled in order inside a housing 40 (FIG. 6) containing the main body of this toroidal type continuous variable speed transmission therein. Accordingly, the deviation of the positional relations among the respective portions based on the integration of the dimensional errors of the constituent parts, and further whether the constituent parts function properly could be confirmed only after these constituent parts were all assembled in the housing 40. In contrast with this, to secure the efficiency and durability of the toroidal type continuous variable speed transmission, the positional relations among the constituent parts must be maintained highly accurate. Therefore, when the deviation of the positional relations of the respective portions becomes great on the basis of the integration of the dimensional errors of the constituent parts, the disassembly and reassembly of the toroidal type continuous variable speed transmission assembled in the housing 40 must be done to make this deviation small by the combination with other parts. When the work of assembling the toroidal type continuous variable speed transmission is done in this manner, the work of manufacturing the toroidal type continuous variable speed transmission is cumbersome and a reduction in cost cannot be achieved.
In view of such circumstances, a power roller unit 41 for a toroidal type continuous variable speed transmission as shown in FIGS. 7 and 8 of the accompanying drawings is described in Japanese Patent Application Laid-Open No. 11-153203. This power roller unit 41 for a toroidal type continuous variable speed transmission has radial needle bearings 22a, 22b which are first radial bearings provided around pivots 5b, 5b secured concentrically with each other to the opposite end surfaces of a trunnion 6. Also, the support shaft portion 25 of a displaceable shaft 7 comprising a support shaft portion 25 and a pivotally supporting shaft portion 26 parallel to and eccentric from each other is rotatably supported in a circular hole 24 formed in the intermediate portion of the trunnion 6 in a direction perpendicular to the axial direction of the pivots 5a, 5b, through a radial needle bearing 27 which is a second radial bearing.
Also, a power roller 8 is rotatably supported around the pivotally supporting shaft portion 26 through a radial needle bearing 28 which is a third radial bearing. Also, between the outer side of the power roller 8 and the inner side of the intermediate portion of the trunnion 6, a thrust ball bearing 29 and a thrust needle bearing 30 which are first and second thrust bearings, respectively, are provided in series with each other with respect to the acting direction of a thrust load. The trunnion 6, the radial needle bearings 22, 27, 28, the displaceable shaft 7, the power roller 8, the thrust ball bearing 29 and the thrust needle bearing 30 which are parts discrete from one another are pre-assembled into the positional relation after the completion of the assembly of the toroidal type continuous variable speed transmission before they are assembled to the toroidal type continuous variable speed transmission.
In the case of the power roller unit 41 for the toroidal type continuous variable speed transmission constructed as described above, the deviation of the positional relations among the respective portions based on the integration of the dimensional errors of the constituent parts, and further whether the constituent parts function properly can be confirmed before these constituent parts are assembled in the housing. Accordingly, without requiring the cumbersome work of disassembling and reassembling the entire toroidal type continuous variable speed transmission, the positional relations among the constituent parts can be maintained highly accurate to secure the efficiency and durability of the toroidal type continuous variable speed transmission.
As described above, Japanese Patent Application Laid-Open No. 11-153203 describes a power roller unit for a toroidal type continuous variable speed transmission which can efficiently effect the assembly of a toroidal type continuous variable speed transmission of high performance, but does not describe means capable of efficiently measuring whether the constituent parts of this power roller unit for the toroidal type continuous variable speed transmission function properly.
In view of such circumstances, the present invention has been made in order to realize a measuring apparatus which can efficiently measure whether the constituent parts of the above-described power roller unit for the toroidal type continuous variable speed transmission function properly.
Any of the measuring apparatuses of the present invention for a power roller unit for a toroidal type continuous variable speed transmission is for measuring the movement of the power roller unit for a toroidal type continuous variable speed transmission before the assembly thereof to the toroidal type continuous variable speed transmission. Also, the power roller unit for the toroidal type continuous variable speed transmission which is the object of measurement comprises a trunnion having concentric pivots secured to the opposite end surfaces thereof, a pair of first radial bearings provided around these two pivots, a circular hole formed in the intermediate portion of the trunnion in a direction perpendicular to the axial direction of the pivots, and a support shaft portion and a pivotally supporting shaft portion parallel to and eccentric from each other, and is provided with a displaceable shaft rotatably supporting the support shaft portion inside the circular hole through a second radial bearing, a power roller rotatably supported around the pivotally supporting shaft portion through a third radial bearing, and first and second thrust bearings provided between the outer side of this power roller and the inner side of the intermediate portion of the trunnion in series with each other with respect to the acting direction of a thrust load. The trunnion, the first, second and third radial bearings, the displaceable shaft, the power roller and the first and second thrust bearings which are parts discrete from one another are pre-assembled into the positional relation after the completion of the assembly of the toroidal type continuous variable speed transmission before they are assembled to the toroidal type continuous variable speed transmission.
Particularly, the measuring apparatus for a power roller unit for a toroidal type continuous variable speed transmission is provided with a pair of pedestals, hold-down means for a pivot, hold-down means for a power roller, pivotally driving means and pivotal displacement measuring means, the pedestals support the pivots provided at the opposite end portions of the trunnion on the upper surfaces thereof through the pair of first radial bearings with the power roller positioned above the trunnion. Also, the hold-down means for the pivot holds down the first radial bearings on the upper surfaces of the pedestals. Also, the hold-down means for the power roller holds down the power roller toward the trunnion. Also, the pivotally driving means presses the two diametrically opposite locations of the power roller with respect to the widthwise direction of the trunnion to thereby pivotally displace the power roller about the support shaft portion. Also, the pivotal displacement measuring means measures the amount of displacement of the power roller by the pivotally driving means.
Also, a measuring apparatus for a power roller unit for a toroidal type continuous variable speed transmission is provided with axially driving means and axial direction displacement measuring means, a pair of pedestals, hold-down means for a pivot and hold-down means for a power roller. The axially driving means presses the axially opposite end surfaces of the displaceable shaft to thereby displace this displaceable shaft axially thereof. Further, the axial direction displacement measuring means measures the amount of displacement of the displaceable shaft by the axially driving means with respect to the axial direction thereof.
According to the measuring apparatus of the present invention for a power roller unit for a toroidal type continuous variable speed transmission constructed as described above, the amount of displacement for judging whether the constituent parts of the power roller unit for the toroidal type continuous variable speed transmission function properly can be measured efficiently.
First, according to the measuring apparatus of the invention, the amount of pivotal displacement for judging Whether a displacement shaft rotatably supporting a power roller around the pivotally supporting shaft portion thereof through a third radial bearing is properly pivotally displaced about a support shaft portion supported relative to a trunnion by a second radial bearing provided inside a circular hole can be measured efficiently.
Also, according to the measuring apparatus of the invention, the amount of axial displacement for judging whether the displaceable shaft supporting the power roller for rotation and pivotal displacement relative to the trunnion is assembled to the trunnion and the power roller with a desired axial gap can be measured efficiently.